Manufacture of smokeless powder



ne ratntedootw, 2,175,212

UNITED ST T PATENT OFFICE MANUrAorUaa or SMOKELESS rownaa Fredrich lsen,.Gordon C. Tlbbitts and Edward B. W. Kerone, Alton, Ill., assignorsv to Western Cartridge Company, East Alton, Ill., a corporation of Delaware No Drawing. Application July 10, 1935, Serial No. 30,634

6 Claims. (01. 52-20) This invention relates generally to the manu-. such as water, to wash out and disperse the facture of explosives and particularly to a process centers of high acidity. It is also desirable to add of manufacturing propellant powder from deto the slurry a sufficient quantity of a neutralizteriorated nitrocellulose powder as the raw mateing' agent, such as calcium carbonate or other rial and pertains particularly to purification and mild alkali, so as to neutralize the acid which stabilization of such deteriorated nitrocellulose to may be washed out of the'comminutednitrocelan extent sufflcient to adapt it for use as a propellulose. In order to facilitate distribution and lant. liberation of. the nitrated centers, which may Nitrocellulose in general and cannon powderin consist of nitrated diphenylamine, the deter- 10 particular decompose in spots. These, spots are iorated nitrocellulose may be softened as by centers of high acid content and contain no untreatment with a suitable solvent and this may nitrated diphenylamine to absorb the acid which evenbe carried out to the extent of forming a is being liberated. Furthermore, while diphenyllacquer solution as described in our copending amine is a neutral amine, its nitration products application Serial No. 598,332 new Patent No.

nitrosodiphenylamine, nitrodiphenyl amine, di- 2,027,114 granted January 7, 1936, where the nitrodiphenylamine and trinitrodlphenylamine lacquer is made using a solvent for nitrocellulose I are acidic, and in large quantities, such as are which is substantially immiscible with water, for present in one of these spots, may be antagonistic instance, ethyl acetate. By this action the nitric toward nitrocellulose. Various decomposition acid present in the spots is liberated and spread products such as ether peroxide formed by oxidauniformly throughout the bath of water. This tion of the residual ether, ethyl nitrate formed is important'since a small amount of acid uniby alcoholysis of the nitrocellulose by the residual formly distributed through intro-cellulose might alcohol, and the possible presence of cellulose not be harmful, whereas this same quantity of nitrite would help explain theunstable character acid when locally concentrated would be inof some cannon powders.=. jurious. The acidic nitrated diphenylamlnes are The object of the present invention, generally also brought into homogeneous solution, and distated, is to provide a process of purifying un phenylamine which could not be reached by the stable or partially decomposed nitrocellulose to nitric acid is brought into intimate contact therean extent suflicient to adapt it ..for.-use as a with. More diphenylamine is usually added to p p the solution as a further safeguard.

A further object of this invention is to pro- In accordance with this invention, therefore,

vide a process of treating deteriorated nitrocelthe series of purifying steps may include grinding I lulose containing centers of high acid concentraand washing only, softening and washing only or i tions whereby to disperse the acid and render the the combination of grinding (with or without subnitrocellulose suitable for use. sequent washing) and softening and washing. 35

A more specific object of this invention is to When the softened dissolved, or partially disprovide a p o ess for ec iming deteriorate solved or gelatinized nitrocellulose is washed with Cannon powder wherein t te s 0f h gh acid water containing calcium carbonate, acid dif- Co cent at o a e d sp rse utilized a d W s fuses out of the nitrocellulose into the water and 40 Out to an extent sumcient to adapt the nitroeelis neutralized. This alkaline medium also has' a 40 1111056 for use as a p pellant. hydrolyzing action upon any unstable esters other Objects Will become pp to those which may be present and the solvent action of Skilled in the art e the following descrip o the water frees the solution of ether peroxide if is read. such is present.

In accordance wi h his inv generally Amild alkaline material like calcium carbonate 45 stated, nitrocellulose which has deteriorated or w chosen for th following reasons; w contains centers of high acid concentration, as is cium carbonate is suspended in water some of it fr q t y p s in a d cann n powder. may dissolves setting up the following equilibrium: be purified and stabilized to an extent sufficient to render it suitable for use as a propellant. This Caco3 caco3+2H2ofCa+2oH+H2Co3 50 solid dissolved may be conveniently accomplished, in accordance with one embodiment of this invention, by grind- Theroncentraflvn of 0H ion is la n u h t ing the deteriorated nitrocellulose powder, as for neutralize acids (which shifts the equilibrium to instance in a water slurry, and thereafter agitatthe right) but not large enough to injure the ing the slurry in a suflicient quantity of a vehicle, nitrocellulose. As soon as some of the OH ions 55 are neutralized, more undissolved calcium carbonate dissolves and hydrolyzes.

Suflicient fresh diphenylamine may then be added to the softened nitrocellulose in order to compensate for that portion of the diphenylamine previously present which has become nitrated and been diffused or liberated by the reclaiming process of the present invention. In order to accomplish this, fresh diphenylamine may be incorporated with the solvent with which the deteriorated nitrocellulose is first softened, or may be applied in a suitable manner after the washing and neutralization is completed.

As an illustrative embodiment of the present invention, grains of completely gelatinized, but partially deteriorated nitrocellulose cannon powder, which contain unstable regions, may be finely divided in a suitable machine, such for instance, as by a beater. This grinding may be carried out in buffered water of a pH value above 7.2 until the material is fine enough to pass, for instance, an 80 mesh screen. This treatment concurrently comminutes and washes the powder, and alone accomplishes a noticeable improvement inthe stability of the powder.

Further improvements in the stability, however, may be accomplished by carrying out either of the processes of graining described and claimed in our prior copending applications Serial No. 598,332, filed March 12, 1932, and Serial No. 620,302, filed June 30, 1932 with suflicient of an alkaline substance, such as calcium carbonate, in the water of the graining bath to neutralize the acid which may be liberated or washed out of the nitrocellulose during the graining process. In the case of the former application the nitrocellulose lacquer is washed by agitation in the water bath while in the latter case softened nitrocellulose particles are similarly washed. As to common subject matter this application may be regarded as a continuation in part of said prior applications Serial No. 598,332 now Patent No. 2,027,114, and Serial No. 620,302.

As a further example, freshly nitrated nitrocellulose which is to be dissolved, gelatinized, or even softened to form grains may be purified by washing the lacquer or softened nitrocellulose as above described. For instance, if gun cotton or nitrated wheat straw paper is used as the raw material in the process of application Serial No. 598,332, the final washing stages of the usual nitration process may be omitted. Hence the bulk nitrocellulose after nitration and having only one or two washings is still in a more or less impure condition, but in this condition it may be dissolved, or merely softened, by the action of a solvent and washed. Of course, if free nitric acid is present in the softened or dissolved nitrocellulose the washing water may be made mildly alkaline, as by the addition of calcium carbonate as above described. Accordingly, final purification of fresh nitrocellulose is thereby accomplished concurrently with the graining operation.

From the foregoing description it is apparent that many modifications of the process hereinbefore described will present themselves to those skilled in the art without departing from the spirit of this invention. It is to be distinctly understood, therefore, that the embodiments hereinbefore described are merely illustrative of the procedure which may be followed but that the invention is not limited thereto. Such modifications and the use of such individual features and such subcombinations of features as do not depart from the spirit of this invention are, although not specifically described hereinbefore, contemplated by and within the scope of the appended claims.

Having thus described the invention, what is claimed is:

1. In the art of treating deteriorated nitrocellulose containing regions of acid concentration, the process comprising, softening the nitrocellulose with a solvent therefor, which is immiscible with water, and washing the solution in a bath of water.

2. In the art of treating deteriorated nitrocellulose containing regions' of acid concentration, the process comprising, softening the nitrocellulose with a solvent therefor, washing the softened nitrocellulose in a mildly alkaline bath, and adding additionalestabilizenwhilethe nitroe. cellulose is soft.

"35 In theart of purifying nitrocellulose the process comprising, treating nitrocellulose containing acidic'impurities with a solvent for nitrocellulose until softened or dissolved, and washing the nitrocellulose while thus softened or dissolved in a mildly alkaline bath in a bath in which the solvent is immiscible.

4. In the art of treating impure nitrocellulose, the process comprising, treating the nitrocellulose with a solvent therefor until the nitrocellulose is dissolved, said solvent being substantially immiscible with water, and agitating the solution in a bath of water sufiiciently alkaline to neutralize acid washed from the nitrocellulose solution.

5. In the art of treating deteriorated nitrocellulose containing ingredients which tend to produce acidic impurities, the process comprising, softening the nitrocellulose with a solvent therefor which is immiscible with water, and washing the solution in a bath of water.

6. In the art of purifying nitrocellulose the process comprising, treating nitrocellulose containing ingredients tending to produce acidic impurities with a solvent for nitrocellulose until softened or dissolved, and washing the nitrocellulose While thus softened or dissolved in a mildly alkaline bath in which the solvent is immiscible.

FREDRICH OLSEN. GORDON C. 'I'IBBIT'IS. EDWARD B. W. KERONE.

:2 CERTIFICATE OF CORRECTION.

Patent No. 2,175,212. I October 10,; 1959.

FREDRICH OLSEN, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2', second column, I line 58, claim 5, strike out the words "in a bath"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of January, A. D. 19LLO.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

